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A levee, dyke , embankment , floodbank or stopbank is a natural or artificial slope or wall to regulate water levels. It is usually [|earthen] and often [|parallel] to the course of a [|river] or the coast. [|[1]] Natural levees Levees are commonly thought of as man-made, but they can also be natural. The ability of a river to carry sediments varies very strongly with its speed. When a river floods over its banks, the water spreads out, slows down, and deposits its load of sediment. Over time, the river's banks are built up above the level of the rest of the [|floodplain]. The resulting ridges are called natural levees. When the river is not in flood state it may deposit material within its channel, raising its level. The combination can raise not just the surface, but even the bottom of the river above the surrounding country. Natural levees are especially noted on the [|Yellow River] in [|China] near the sea where oceangoing ships appear to sail high above the plain on the elevated river. Natural levees are a common feature of all meandering rivers in the world. Artificial levees The main purpose of an artificial levee is to prevent flooding of the adjoining [|countryside] ; however, they also confine the flow of the river, resulting in higher and faster [|water] flow. Levees can be mainly found along the sea, where dunes are not strong enough, along rivers for protection against high-floods, along lakes or along polders. Furthermore, levees have been built for the purpose of [|empoldering], or as a boundary for an inundation area. Levees can be permanent [|earthworks] or emergency constructions (often of [|sandbags] ) built hastily in a flood emergency. When such an emergency bank is added on top of an existing levee it is known as a cradge. How the processes of erosion deposition and transportation has helped formed levees
 * __Levees__**

Man made levees are only effected by the process of erosion as the water and the sediment in the water will erode the sides of the levee walls, when a flood occurs sometimes the water and sediment erodes the levee walls faster than expected and can result in the breach of the levee, and flooding of the surrounding land area, and example of this is the Mississippi river at New Orleans.

Natural levees are effected by all process, the river in the upper course will erode its bed and the banks and transport this sediment down the river towards the middle and lower course of the river and here when a river floods the river deposit’s the sediment been transported as close to the river as possible, so on top of the banks, these particles of rocks, pebbles, sand, silt and clay for mounds on the sides of the river above the height of the surrounding land, these are natural levees.

Examples: Mississippi river, USA (man made) and Yellow river, China (natural) The Mississippi levee system represents one of the largest such systems found anywhere in the world. They comprise over 3,500 miles (5,600 km) of levees extending some 1,000 miles (1,600 km) along the Mississippi, stretching from [|Cape Girardeau, Missouri] to the [|Mississippi Delta]. They were begun by French settlers in [|Louisiana] in the 18th century to protect the city of [|New Orleans]. The first Louisianan levees were about 3 feet (0.9 m) high and covered a distance of about 50 miles (80 km) along the riverside. By the mid-1980s, they had reached their present extent and averaged 24 feet (7 m) in height; some Mississippi levees are as much as 50 feet (15 m) high. The Mississippi levees also include some of the longest continuous individual levees in the world. One such levee extends southwards from [|Pine Bluff, Arkansas] for a distance of some 380 miles (611 km). The yellow river levee system can hold a flood discharge of up to 2,2300 m3/s. Due to its heavy load of silt the Yellow River is a [|depositing stream], that is, it deposits part of its carried burden of soil in its bed in stretches where it is flowing slowly. These deposits elevate the riverbed which flows between [|natural levees] in its lower reaches. Should a flood occur, the river may break out of the levees into the surrounding lower flood plain and adopt a new course. Historically this has occurred about once every hundred years. In modern times, considerable effort has been made to strengthen levees and control floods. The reason for this easy flooding is because the natural levees are made up of mainly silt which when the river rises just washes the silt away and easily breaks through onto the nearby land. As the Chinese developed agriculture on the plain, they became more adept at building [|levees] to stabilize the channel and thereby protect the inhabitants against the  [|floods] brought by shifts in the channel. Tens of thousands of miles of levees have been constructed through the centuries. The overall effect of these has been to delay flooding, but, because the riverbed has been elevated and confined artificially, levee breaching and channel shifts have become more dramatic and destructive than they otherwise would have been. The few hydraulic engineers who succeeded in decreasing rather than increasing the flood hazard have gained legendary status in Chinese history. Breaks in the levees have been more frequent than course changes throughout history. Between 960 and 1048 there were 38 major breaks and 29 more were recorded from 1048 to 1194. In later years such breaches were less frequent as a result of systematic improvements to the levee system. Levees are used by humans to prevent flooding in the land adjacent to the river; they are either man made or natural. The man made levees are usually around 15 feet high and made of an impermeable metal, rock, or concrete so the water cannot pass through the levee in the case of the river being high.